So you have a visitor that your dog 'doesn't like', so you have this dog locked up?  This cancels everything you expect your dog to do!  What if this person is the bad guy?  Your dog, to be effective, needs to be a polite presence with visitors, and under your control, because you have let them in.  If something goes really wrong, then your trained dog can get between you, or be a distraction, or whatever.
What's best for most of us is a basically friendly dog who can be impressive but manageable.  I think your best bet is to get a dog who basically likes people, isn't the boss puppy in the litter, and isn't back in the corner either, and then invest in the training and socialization necessary to have a well behaved family member, while guarding appropriately.  Biting is last on the list!
Mary